Gut training

Working out may help you work it through. New research suggests strength training may rev up gastrointestinal transit time--how long it takes for food to get from the mouth through the stomach and intestines.

In a study of seven healthy but untrained men undergoing a 13-week strength-training program, bowel transit time accelerated by roughly 56 percent , compared to a no-exercise period before training (Medicine and Science in Sports and Exercise, April 1992).

"All men showed improvements," says Ben F. Hurley, Ph.D., director of the exercise labat the University ofMaryland College of Health and Human Performance, who supervised the study conducted by Karen Koffler, M.A., R.D. Studies do suggest that populations with the highest rates of colon cancer also tend to have slow transit times.

"If slow transit time increases one's risk of colon cancer, then strength training may be one way to reduce that risk factor," Dr. Hurley says. Slow transit time is also linked to other age-related gastrointestinal disorders like diverticulosis and constipation. "Right now, however, we're a long way from knowing for sure if this kind of exercise may actually prevent these illnesses," says the researcher.

This is the first study to link strength training to a speedier gut, and right now it's a stab in the dark as to why it occurs."How strength training exerts its effect is still up in the air, but it may have to do with the exercise's effect on a gastrointestinal hormone called motilin, which has been shown to increase during aerobic exercise," says Dr. Hurley. Higher levels of that hormone somehow may be related to an accelerated transit time.

Another possible explanation may lie in the mechanics of the abdominal exercises the men performed. "The muscular contractions from the abdominal exercises occur closest to where the intestinal tract is," says Dr. Hurley. "We'll need more studies, though, to really uncover the mechanism involved."